In cane harvesters, it is important to have structural rigidity in the area of the chopper drums. This is so because the knives of the chopper drums are in close proximity throughout their longitudinal length which extends across substantially the transverse distance between the frame sections. Failure to provide this structural rigidity can cause damage to the knives and chopper drums and can cause uneven billet cutting.
Further, since the chopper drums are located in the rearward portion of the harvester, they were subject to the considerable loading effects caused by the elevator. In adjacent row cutting harvesters, these loads are considerable.
Previously, structural reinforcement steel was provided to obtain frame integrity. This was unsatisfactory because it was expensive and added unwanted weight to the harvester.
A further problem in the structure of harvesters occurs in the forward crop gathering area. In this area, the harvester necessarily must have a hollow area between the frame sections to allow crop to pass therethrough to the basecutters. Because the height of cane is significant, this hollow area can extend upwardly a good distance thus adversely affecting the structural rigidity of the frame. Previously, structural steel was also used in this area to provide structural integrity. As stated, such use is expensive and increases the weight of the harvester.
Yet a further problem occurred in the area of the engine compartment mounting. Previously, the engine was located at an elevated position on the harvester and it was desirable, for stability purposes, to lower the engine. Lowering the engine, however, required a substantial reduction in the height of the frame sections supporting the engine which, again, adversely affected the load carrying ability of the frame sections.
Chopper drums on cane harvesters cut the cane passing through the harvester into billets which are used in the sugar cane milling and refining process. This cutting subjects the chopper drums to severe shock loads because of differences in the quantity of crop passing between the knives of the chopper drums and because of the existence of rocks and other debris which have not been disposed of before arriving at the chopper drums.
Previous chopper drums included a solid shaft extending from each end of the chopper drum. The shaft was mounted in bearing housings in the frame of each side of the harvester. External to the bearings on one side, a splined adaptor plate was attached to the end of the chopper drum which provided the timing and the drive to the chopper drum.
In the event of damage to the chopper drum, the splined shaft or the internally splined adaptor plate, the entire assembly had to be replaced which was expensive. Further, it was necessary to remove the entire assembly through the frame which was time consuming and unnecessary.
Cane harvesters have evolved from low capacity machines used for intermittent cane cutting at infrequent intervals to high capacity machines which are intended to be used 24 hours per day in various locations. As such, the ease of servicing harvesters and their transport to various locations becomes of considerable importance.
Previously, the elevators of harvesters would be removed for transport where overhead instructions such as wires or overpasses were present. This was required because the cleaning chamber design of such harvesters did not permit the elevators to be raised or lowered except for a very limited amount of movement. Removal and refitting of the elevators was time consuming and complicated and required the service of a crane. It was also unnecessary.
Further, to service the higher areas of the elevator, the operator would have to climb up the elevator. This was inconvenient and dangerous.
It is necessary, particularly for cane harvesters used in harvesting green cane; that is, cane that has not been burned prior to harvesting, that the throat area through which the cut cane passes be as wide and as unobstructed as possible. This is so because of the large amount of crop material that must pass through the throat and be cut by the basecutters. A large throat area will increase capacity as will the removal of obstructions therein.
The width of the throat, however, is restricted by the cane cutting capabilities of the machine itself. While it is possible to increase throat size, that size is limited if it is desired to have a machine which is capable of cutting adjacent rows of cane in either direction. It is known, for example, to use a large throat area in certain harvesters. Such harvesters are restricted, however, to `perimeter cutting`; that is, such harvesters cannot cut adjacent rows in either direction. Rather, such harvesters are restricted to cutting around the perimeter of the cane field with ever increasing or decreasing distances between rows to be cut depending on how the operator operates his harvester. Such a practice is inefficient and results in unacceptable unused or `down` time for such harvesters. Thus, throat size is, in practice, limited in transverse width.
When utilizing harvesters for adjacent row cane cutting it is also desirable to locate the severing area of the basecutters as close as possible to an imaginary line joining the forward harvester tires where the tires contact the ground surface. This is so because the basecutters will then follow the ground contour more closely and sever the cane very close to the cutting level selected by the operator thus avoiding wastage of cane or damage to the basecutters. If the basecutters are located forwardly or rearwardly of such an imaginary line, a "cantilever" or bridging effect is obtained which can make the basecutters vulnerable to damage from inadvertent contact with the ground surface or, as explained, increase the distance from the ground at which the cane is severed.
Previous adjacent row cutting harvesters utilized a gearbox located above the basecutters and connected thereto by drive shafts, one for each basecutter, extending downwardly from the gearbox. These drive shafts and the gearbox caused throat obstructions which, while causing no appreciable capacity difficulties when cutting burned cane, lessened that capacity when cutting green cane. The shafts were also subject to damage when forces from unusually large rocks were encountered because of the length of these drive shafts from the gearbox to the basecutters.
Basecutters of a smaller rather than a larger diameter are also desirable. This is so because the side profile of basecutter discs is desirably slanted from front to back in order to cut near the ground level. With basecutter discs of larger diameter, the cutting area of the basecutters is located substantially behind the forward most point of the basecutters and, therefore, at a higher distance above the ground level than is necessary. When the cane is knocked down by the top power roller during harvesting and particularly when cutting burned cane, the cane may escape beneath the basecutters without being cut. This is obviously undesirable.
Top rollers are used in cane harvesters to separate the cane stalks and to knock down the cane as the machine proceeds during its cutting operation. Fins are used on the top roller to separate the cane which enhances the cane cutting and the conveying of the cut cane in the feed passage to the chopper rolls. When cutting green cane, the amount of material may cause the top roller to become fouled with crop material. To remove this material, the top roller may be reversed.
The profile on the fins of previous top rollers, however, caused additional material jamming because the rearward surface of the fins contained a concave surface.